The present invention generally relates to a blood clarification apparatus. More particularly, the present invention relates to a blood clarification apparatus, wherein occurrence of hypotension attack can be effectively prevented during dialysis/filtration operation, and safety and operation characteristics can be effectively improved.
Recently, a medical treatment by blood clarification, using a so-called artificial organ, is generally employed and its distinguishing effect is recognized. During treatment, blood once taken out from a living body is circulated through a housing enclosing a semipermeable membrane; the blood is subjected to a predetermined clarifying action by dialyzing or filtering action with the semipermeable membrane; the amount of the blood is controlled by removal of water; and thereafter the blood is brought back into the living body. Thus, renal function and liver function are artificially achieved. For example, a medical treatment by blood dialysis or filtration with the use of a so-called artificial kidney, which is applied to a renal insufficiency patient, is a typical one.
Hereupon, in carrying out blood clarification with an artificial kidney, it is necessary to take out blood from a spot of a living body where enough blood can be obtained. Since enough blood is difficult to be obtained from a vein existing in a vicinity a body surface, a shunt operation is generally performed. The shunt is an operation wherein, for example, at a region such as an arm, one of the arteries existing in a deep area of a body is connected with a vein existing in a vicinity of a body surface to bypass them. By this method, an amount of blood running through a vein can be increased. Then, a thick needle (a puncture needle) generally of 15 to 17 gage is used to puncture the fistula (namely, the arteried vein); and blood is taken out at a rate of about 250 ml/min by using a blood pump to lead the blood to a clarification device. In this device, clarification and removal of water in the blood are carried out.
Due to the above-mentioned treatment, a phenomenon sometimes occurs wherein blood pressure is abnormally lowered during the dialyzing, in a certain patient undergoing medical treatment by the blood dialyzing (the word "dialyzing" used hereinafter includes filtration). This sharp lowering of blood pressure causes symptoms of vomiting and cramp, and loss of awareness. In an extreme case, the lowering of blood pressure may endanger the life of a patient. This is a so-called dialysis hypotension. It is recognized that 10 to 20% of all patients received shock two or three times in one medical treatment by blood dialyzing.
In order to prevent the occurrence of dialysis hypotension symptoms during the dialysis operation, it is necessary to measure blood pressure of the patient continuously and to consider counterplans such as control of water-removing-rate and/or supply of supplementary fluid into blood based on the change of blood pressure.
However, since conventional dialysis apparatus does not have a suitable means for automatically measuring blood pressure, it is necessary for a nurse or such person to measure blood pressure at a predetermined time interval by usual ausculation, and to manually control the water-removing-rate or supply supplementary fluid. The operation takes a great deal of trouble for the patients and operators. Moreover, since the dialysis hypotension occurs at intervals of one or two minutes, it is very difficult to immediately find the occurrence of the shock as well as to predict the occurrence of the shock based on the above-mentioned measurement of blood pressure at a predetermined time interval. For this reason, the counterplan for the shock is likely to be late.
Hitherto, in order to measure blood pressure in a blood vessel, a needle has been produced having two apertures parallel to each other wherein one of the apertures is utilized for taking out blood from a blood vessel and the other is utilized for transmitting blood pressure inside the blood vessel to a pressure transducer. However, the needle having two apertures is expensive because of its complicated producing steps. Further, since its outer diameter becomes much thicker than that of conventional puncture needles, the blood stanching is very difficult after taking out the needle. For these reasons, the needle having two apertures has not been used practically.
The present invention was made to solve the above-mentioned drawbacks, and it is thus an object of the present invention to prevent the dialysis hypotension by continuously and automotially measuring blood pressure during dialysis/filtration operation and by enabling the control of water-removing-rate or supply of supplementary fluid based on measurement of blood pressure.